The present invention relates to automatic equipment in general for packaging products, for example food products such as biscuits, chocolate bars, etc.
More precisely, the present invention relates to a packaging system in which the products to be packaged advance from a supply station towards a handling station which is situated downstream of the supply station in the direction of flow of the products and which may stop for certain periods of time, motor-driven conveyor means being interposed between the supply station and the handling station for collecting products which accumulate during periods of stoppage of the handling station.
In known embodiments of such a system, the conveyor means are usually constituted by a conveyor of sufficient length to be able to hold a quantity of accumulated products which corresponds substantially to the quantity of products which emerges from the supply station during a period of time substantially equal to the maximum period of stoppage envisaged for the handling station. Naturally, in the event of a longer stoppage of the latter station it is necessary to provide a function for discharging (dumping) the products which continue to emerge from the supply station at some point in the system.
Even if the problem of product wastage is disregarded, the prior-art storage solutions can certainly not be considered optimal for various reasons.
In the first place, when the handling station is restarted, the first products transferred to it may not be arranged ideally.
This is particularly true when one considers that, in most systems of the type specified above, the products normally advance with a forward or backward inclination, in a partially-superposed condition ("shingled" or "stacked", according to current English terminology) but, in accumulated conditions, are packed closely together, in face-to-face contact (that is in a vertical position).
While a row of partially-superposed products (shingled or stacked) still has a certain capacity to contract longitudinally, a row of products in close contact (that is "packed") is practically incompressible so that the products which are furthest forward in such a pile of closely-packed products are subject to considerable pressure from the products which gradually accumulate upstream with the consequent risk that the products may break and soil the equipment, possibly stopping the handling station again just as it is being restarted or a short time thereafter.
The problems outlined above are even more serious when it is considered that systems of the type specified are usually made to deal with several flows ("lanes") of products in parallel. This means, for example, that the quantity of products wasted in the event of discharge (dumping), or damaged as a result of excessive pressure, can be quite considerable.
Moreover, the operation of the system is made even more critical by the fact that, even if the operating speed of the handling unit is kept rigorously constant (in terms of items accepted per minute), the corresponding speed of linear advance of the products (identified by the number of products dealt with per unit time multiplied by the space occupied by each product) may vary, for example, due to a variation in the thickness of individual products: this is the case, for example, with some baked products such as biscuits and the like for which it is certainly not possible to ensure that very strict dimensional tolerances are respected absolutely.
The rate at which the products are supplied by the supply station (for example an oven) may also be subject to significant variations, for example as a result of an event which leads to the discarding of a quantity of products which are not acceptable from a qualitative point of view, for example, overcooked biscuits.
As a result, even if the speed at which the products are taken in by the handling unit is regulated so as to correspond generally with the rate of supply of products from the supply station, it is necessary to interpose product conveyor means between the two stations to absorb random variations without damaging the products and/or leading to excessive wastage thereof.